Grinding machine for machining a sweep edge of a rotor blade

Abstract

The invention relates to a grinding machine (1) for machining a rubbing edge (2) of a guide vane (3), comprising a grinding unit (4) with a driven grinding tool (5), a workpiece holding device (6) which is configured to receive a guide vane (3) to be ground, and a workpiece drive unit (7) which is designed to move the workpiece holding device (6) with a guide vane (3) received thereon relative to the grinding tool (5) for machining the rubbing edge (2), wherein the workpiece drive unit (5) has a pivot axis (28) on which the workpiece holding device (6) is held such that the rubbing edge (2) of a guide vane (3) received thereon is brought into engagement with the grinding tool (5) during a pivoting movement of the workpiece holding device (6) about the pivot axis (28).Furthermore, the invention relates to a method for machining a rubbing edge (2) of a guide vane (3), in particular using a grinding machine (1) according to the invention.

Description

[0001] The present invention relates to a grinding machine for machining a squealer edge of a rotor blade, comprising a grinding unit with a driven grinding tool, a workpiece holder configured to hold a rotor blade to be ground, and a workpiece drive unit configured to move the workpiece holder with a rotor blade mounted thereon relative to the grinding tool for machining the squealer edge. Furthermore, the invention relates to a method for machining a squealer edge of a rotor blade, in particular using such a grinding machine.

[0002] Rotor blades, such as those used in gas turbines in particular, are exposed to extreme conditions during operation, resulting in significant wear, primarily caused by oxidation. Accordingly, worn rotor blades must be regularly replaced with new or overhauled rotor blades as part of a gas turbine overhaul. The new rotor blades to be installed must be individually adapted to the existing gas turbine at each construction site. The length of the rotor blade is reduced at the squealer edge to adjust the distance between the squealer edge of the rotor blade and the gas turbine casing so that the gap is as small as possible during gas turbine operation, thus minimizing unwanted gap losses.

[0003] Grinding machines are typically used to shorten the squeal edges of rotor blades. These typically comprise a stationary grinding unit with a driven grinding tool, a workpiece holder configured to hold a rotor blade to be ground, and a workpiece drive unit designed to move the workpiece holder with a rotor blade mounted thereon relative to the grinding tool for machining the squeal edge. The workpiece drive unit and the associated control system of such grinding machines are designed to enable circular interpolation, which is necessary to produce the complex geometry of the squeal edge in the form of a conical section.

[0004] Based on this prior art, it is an object of the present invention to provide an alternative grinding machine and an alternative method of the type mentioned at the outset for machining a squealer edge of a rotor blade.

[0005] To achieve this object, the present invention provides a grinding machine of the type mentioned above, which is characterized in that the workpiece drive unit has a pivot axis on which the workpiece holding device is held in such a way that the squealer edge of a rotor blade held thereon is brought into engagement with the grinding tool as the workpiece holding device pivots about the pivot axis. Thanks to such a pivot axis, the grinding edges of rotor blades can be easily provided with a wide variety of conical section shapes without complex CNC-controlled circular interpolation and with a simple design. For this purpose, the grinding machine according to the invention simulates the actual installation situation of a rotor blade, with the workpiece holding device representing the wheel disc, the pivot axis representing the wheel disc rotation axis, and the grinding tool representing the gas turbine casing.

[0006] According to a first embodiment of the present invention, the grinding tool is a substantially cylindrical grindstone that is driven to rotate about its longitudinal axis. However, according to a second embodiment, a driven grinding belt is preferably used as the grinding tool, which is guided over a contact roller and at least one deflection roller. Such a belt grinder is advantageous in that the grinding belt is relatively inexpensive and can be replaced quickly and easily.

[0007] According to one embodiment of the present invention, a longitudinal axis of the grindstone or a longitudinal axis of the contact roller is arranged parallel to the pivot axis of the workpiece drive unit, at least in a longitudinal axis home position. In such a longitudinal axis home position, squealer edges with a constant outer diameter in the axial direction can be produced.

[0008] Advantageously, a pivoting device is provided on which the grinding unit is pivotably mounted for adjusting the longitudinal axis of the grindstone or the longitudinal axis of the contact roller relative to a longitudinal axis home position. The pivot axis of the workpiece drive unit and the pivot axis of the pivoting unit are preferably arranged perpendicular to each other. Thanks to such a pivoting device, squealer edges with an outer diameter conical in the axial direction can also be produced.

[0009] A vertically extending linear guide is also provided, along which the grinding unit can be moved up and down. Accordingly, in this embodiment of the grinding machine according to the invention, the feed movement is realized by moving the grinding unit along the linear guide.

[0010] Advantageously, an extraction head of an extraction unit is arranged in the area of ​​the grinding unit in order to remove grinding dust that occurs during grinding.

[0011] According to one embodiment of the present invention, the pivot axis of the workpiece drive unit is mounted in a fixed position. This results in a very simple design.

[0012] It is advantageous to provide an externally accessible machine cabin in which the grinding unit and the workpiece holding device are located. Such a cabin serves both to ensure the safety of the operating personnel and to prevent contamination of the surrounding area by accumulating or unextracted grinding dust.

[0013] Advantageously, the machine cabin has a ceiling panel on which the workpiece drive unit is mounted. This results in a very simple and inexpensive grinding machine design.

[0014] The grinding machine is advantageously designed to be transportable as a whole, allowing it to be easily transported to any construction site where maintenance work on gas turbines is to be carried out. The grinding machine can be equipped with eyelets or similar devices for attaching crane straps. Additionally or alternatively, the grinding machine can also have a base plate designed to accommodate a forklift fork.

[0015] To achieve the object mentioned at the outset, the present invention further provides a method for machining a squealer edge of a rotor blade, in particular using a grinding machine according to the invention, in which the squealer edge of a rotor blade is brought into engagement with a grinding tool as part of a pivoting movement of the rotor blade about a specific pivot axis.

[0016] In the method according to the invention, the squealing edge is preferably brought into engagement with the grinding tool during the pivoting movement in such a way that the squealing edge takes on the shape of a conical surface section.

[0017] Further features and advantages of the present invention will become apparent from the following description of a grinding machine according to an embodiment of the present invention with reference to the accompanying drawings.

[0018] This includes Figure 1 is a perspective view of a grinding machine according to an embodiment of the present invention; Figure 2 is a front view of the Figure 1 grinding machine shown; Figure 3 a perspective top view of the upper part of the Figure 1 grinding machine shown, showing a workpiece drive unit; Figure 4 is an enlarged view of a grinding unit and a workpiece holding device of the Figure 1grinding machine shown; and Figure 5 is a perspective view of the Figure 4 shown and arranged on a pivoting device.

[0019] The figures show a grinding machine 1 according to an embodiment of the present invention, which is used to machine a squealer edge 2 of a rotor blade 3.

[0020] The grinding machine 1 comprises as main components a grinding unit 4 with a driven grinding tool 5, a workpiece holding device 6 which is designed to hold a rotor blade 3 to be ground, and a workpiece drive unit 7 which is designed to move the workpiece holding device 6 with a rotor blade 3 held thereon for the purpose of machining the squealer edge 2 of the rotor blade 3 relative to the grinding tool 5.

[0021] The grinding unit 4 is designed as a belt grinder. It comprises a grinding belt as the grinding tool 5, which is guided over a contact roller 8 and two deflection rollers 9 and 10 and can be driven in a known manner via a drive (not shown in detail). A carriage 11 of the grinding unit 4 is movable and lockable on guide rails 12 and 13, which are arranged parallel to one another and are shaped like circular ring segments, of a pivoting device 14, so that the grinding unit 4 can be pivoted as a whole about a pivot axis 15. Accordingly, a longitudinal axis 16 of the contact roller 8 can be adjusted as required during a pivoting movement about the pivot axis 15, starting from a longitudinal axis basic position in which the longitudinal axis 16 extends horizontally. The pivoting device 14 is movable up and down on a vertically extending linear guide 17 and can be locked in any position.This allows the grinding unit 4 to be moved up and down in any pivoting position. A suction head 18 of a suction unit (not shown in detail) is arranged in the area of ​​the contact roller 8, the width of the suction head 18 essentially corresponding to the width of the grinding tool 5.

[0022] The grinding unit 4, the pivoting device 14, and the linear guide 17 are arranged in a machine cabin 19. This comprises a cabin floor 20, side walls 21, an access door 22, a ceiling plate 23, and a cabin roof 24, which is detachably attached to the ceiling plate 24 to cover it. The workpiece holding device 6 is positioned above the grinding unit 4 within the machine cabin 19. The workpiece holding device 6 comprises a clamping device 25, which is designed to receive and clamp a blade root 26 of the rotor blade 3. The clamping device 25 is firmly connected, via an intermediate piece 27, which extends through an opening in the ceiling plate 24, to a pivot axis 28 of the workpiece drive unit 7, which is arranged and mounted on the outside of the ceiling plate 23 of the machine cabin 19.The pivot axis 28 of the workpiece drive unit 7 extends parallel to the longitudinal axis 16 of the contact roller 8 when the latter is in its longitudinal axis home position, and perpendicular to the pivot axis 15 of the pivoting device 14. The pivot axis 28 is connected via a toothed belt 29 to a drive 30, which is also fastened to the outside of the cover plate 23, so that the clamping device 25 with a rotor blade 3 held thereon can be pivoted back and forth about the pivot axis 28 relative to the contact roller 8 of the grinding unit 4 via the drive 30.

[0023] The grinding machine 1 is designed to be transportable as a whole. For this purpose, eyelets (not shown in detail) can be screwed into the ceiling panel 24 of the machine cabin 19. These eyelets serve to attach crane straps, allowing the grinding machine 1 to be lifted using a crane. Furthermore, metal tubes 31 with a rectangular cross-section are attached to the cabin floor 20. Their sizes and spacing are selected such that a forklift fork can be inserted into them. Accordingly, the grinding machine 1 can also be picked up and transported using a forklift.

[0024] To machine a squealer edge 2 of a rotor blade 3, the rotor blade 3 is mounted in a first step in the clamping device 25 of the workpiece holding device 6. Subsequently, a desired setting of the contact roller 8 of the grinding unit 4 is set by pivoting the grinding unit 4 about the pivot axis 15 of the pivoting device 14. In a further step, the clamping device 25 with the rotor blades 3 held thereon is pivoted from the vertical position, as shown in Figure 2is shown. The grinding unit 4 is then moved vertically along the linear guide 17 in order to set the desired infeed. The grinding tool 5 of the grinding unit 4 is now driven, whereupon the clamping device 19 with the rotor blade 3 held thereon is pivoted about the pivot axis 28 of the workpiece drive unit 7 using the drive 30. During this pivoting movement, the squealer edge 2 of the rotor blade 3 is guided over the grinding tool 5 so that material is removed. During this material removal, the squealer edge 2 takes on the shape of a conical surface section. The chips produced during machining are sucked away via the suction head 18.

[0025] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed example, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. For example, instead of a grinding belt, a cylindrical grindstone can be used as the grinding tool.

Claims

1. Grinding machine (1) for machining a squealer edge (2) of a rotor blade (3), comprising - a grinding unit (4) with a driven grinding tool (5), - a workpiece receiving device (6) which is designed to receive a rotor blade (3) to be ground, and - a workpiece drive unit (7) which is designed to move the workpiece receiving device (6) with a rotor blade (3) received thereon for the purpose of machining the squealer edge (2) relative to the grinding tool (5), characterized in thatthe workpiece drive unit (5) has a pivot axis (28) on which the workpiece receiving device (6) is held in such a way that the squealing edge (2) of a rotor blade (3) received thereon is brought into engagement with the grinding tool (5) as part of a pivoting movement of the workpiece receiving device (6) about the pivot axis (28), wherein a vertically extending linear guide (17) is provided, along which the grinding unit (4) can be moved up and down.

2. Grinding machine (1) according to claim 1, characterized in that the grinding tool (5) is a substantially cylindrical grindstone or a driven grinding belt which is guided over a contact roller (8) and over at least one deflection roller (9, 10).

3. Grinding machine (1) according to claim 2, characterized in thata longitudinal axis of the grindstone or a longitudinal axis (16) of the contact roller (8) is arranged at least in a longitudinal axis basic position parallel to the pivot axis (28) of the workpiece drive unit (7).

4. Grinding machine (1) according to claim 2 or 3, characterized in that a pivoting device (14) is provided on which the grinding unit (4) is pivotably received for adjusting the longitudinal axis of the grindstone or the longitudinal axis (16) of the contact roller (8) with respect to a longitudinal axis basic position, wherein the pivot axis (28) of the workpiece drive unit (7) and the pivot axis (15) of the pivoting device (14) are preferably arranged perpendicular to one another.

5. Grinding machine (1) according to one of the preceding claims, characterized in that a suction head (18) of a suction unit is arranged in the area of ​​the grinding unit (4).

6. Grinding machine (1) according to one of the preceding claims, characterized in thatthe swivel axis (28) of the workpiece drive unit (7) is mounted in a stationary manner.

7. Grinding machine (1) according to one of the preceding claims, characterized in that a machine cabin (19) accessible from the outside is provided in which the grinding unit (4) and the workpiece receiving device (6) are arranged.

8. Grinding machine (1) according to claim 7, characterized in that the machine cabin (19) has a ceiling plate (23) on which the workpiece drive unit (7) is arranged.

9. Grinding machine (1) according to one of the preceding claims, characterized in that which is designed to be transportable in its entirety.

10. Method for machining a squealer edge (2) of a rotor blade (3), in particular using a grinding machine (1) according to one of the preceding claims, in which the squealer edge (2) of a rotor blade (3) is brought into engagement with a grinding tool (5) as part of a pivoting movement of the rotor blade (3) about a specific pivot axis (28).

11. Method according to claim 10, characterized in that the squealing edge (2) is brought into engagement with the grinding tool (4) during the pivoting movement in such a way that the squealing edge (2) takes on the shape of a conical surface section.

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